"A presumption of prejudice will only arise in the extreme case," his attorneys said in a 10-page motion. "But this is such a case."

Attorneys said they had enlisted an expert to survey public opinion in four cities: Boston, Springfield, Mass.; New York City and Washington. Respondents were asked a series of questions, including whether they believed Tsarnaev was "definitely guilty, probably not guilty or definitely not guilty" of the April 2013 bombings that left three dead and more than 260 wounded.

In Boston, 58% said they believed Tsarnaev was definitely guilty, as did 52% in Springfield and 48% in Manhattan. Only 37% in Washington said the same.

More than half of the Boston-area respondents (52%) said they had participated in the 2013 marathon, either as a runner or spectator or knew someone who had. Fewer than 12% in Manhattan and Washington said the same. Such experiences contribute to making Boston the most prejudiced of possible trial venues, they argued, in terms of "pre-judgment of guilt" and other factors.

Defense attorneys invoked the Sixth Amendment of the U.S. Constitution, which provides for a right to trial "by an impartial jury of the state and district wherein the crime shall have been committed."

However they also cited case law that "a court must transfer the proceeding â?¦ to another district if the court is satisfied that so great a prejudice against the defendant exists in the transferring district that the defendant cannot obtain a fair and impartial trial there."

Federal prosecutors will be allowed to respond to the change-of-venue request.

Tsarnaev's lawyers noted that the trial of Oklahoma City bomber Timothy McVeigh was moved from Lawton, Okla., to Denver because the court determined there was too much prejudice against him in Oklahoma.

"The community impact here is even greater than that present in McVeigh," wrote attorneys Judy Clarke, Miriam Conrad and David Bruck. They recalled how the region was gripped by "indelible fear that friends or family could have been killed or injured" in the Boston Marathon attacks and how a shelter-in-place order affected hundreds of thousands during the manhunt for Tsarnaev and his brother, who was killed in a shootout with police days after the bombing.

"If a change of venue was warranted in McVeigh," they wrote, "it is even more compelled by the facts presented here."

Tsarnaev's attorneys said more analysis of potentially prejudicial media coverage is warranted but court deadlines have not permitted such research to be completed yet.